We can see that the nominal exchange rate from Discover card statement is even slightly LOWER than the buy/sell medium price from BOC website. The difference is within 1%, but hey it is good. Because it means that when you spend the same amount of CNY in China, you need to pay back less USD.

The swiping experience is good for all the transactions I tried. I swiped it in some clinic in Beijing, bought something in gift shop in a small tourist city, at Walmart in another small city. All went through smoothly. They will ask you to enter pin number, just the press the Green buttom and it will work.